Hi, my first BP post and I need some input, understanding and direction

Situation: in a down 2010 market I purchased ONE piece of property with TWO HOUSES in a very desirable area of Orange County CA. All utilities are separate and because it is a corner lot each home has a separate street address. STILL only ONE property, ONE mortgage, ONE tax ID number. I fixed them up all nice and pretty. I live in one and rent the other. I've gained some valuable renovation and landlording experience and I have saved the rental income to provide me the down payment funds for my next property.

I would now like to establish a HELOC on the property to have funds available for repairs on my next purchase.

Problem: Some big bank lenders and Credit Unions I have gone to get "weird" about establishing a HELOC on my property with TWO houses. They can't get past that its not a duplex and why there are there two different addresses. Some say their charter won't allow the HELOC on my type of property, another wanted to appraise only the house I live in and ignore the value of the other.

Questions:

1. Who (person/bank) can provide me a HELOC based on the value of my property type?

2. Can someone give me some understanding of the underwriters POV so I can have a better understanding. The customer service reps at the branches only repeat what they are told and can't provide me more understanding